##ate and reg ##ios ##ele ##ctive elimination . in addition , the electron withdrawing group increases the acid ##ity of the α @ - @ proton , allowing selective formation of the trans @ - @ α @ - @ ep ##ime ##r via e ##quil ##ib ##ration . it is often possible to achieve catalytic activation using a dona ##ting or withdrawing group alone , although the efficiency of the reaction ( yield , reaction time , etc . ) is typically lower . = = = alternative cat ##ion generation = = = by extension , any pen ##tad ##ien ##yl cat ##ion regardless of its origin is capable of undergoing a na ##zar ##ov cy ##cl ##ization . there have been a large number of
##ate and regioselective elimination. in addition, the electron withdrawing group increases the acidity of the α @ - @ proton, allowing selective formation of the trans @ - @ α @ - @ epimer via equilibration. it is often possible to achieve catalytic activation using a donating or withdrawing group alone, although the efficiency of the reaction ( yield, reaction time, etc. ) is typically lower. = = = alternative cation generation = = = by extension, any pentadienyl cation regardless of its origin is capable of undergoing a nazarov cyclization. there have been a large number of